Stream-type IP multicast networks which use multicast IP addresses to transmit for example video information from one transmission terminal to a large number of members (receiving terminals) are being constructed and are being used by large numbers of users, In this case, this video information is transferred as multicast frames via predetermined routers over the IP network to be provided to predetermined members. At this time, naturally, the video information must accurately reach all of the predetermined members. Further, this video information must not end up being transmitted by mistake to destinations other than those of the predetermined members. that is, the transmission routes of the multicast frames must be the designed transmission routes. Verifying that they are the designed transmission routes is important for, e.g., the carriers.
The above transmission routes, in the case of multicast transmission, form a tree structure on the IP network, therefore such a form of the transmission routes is generally called a “multicast tree”. To verify that the multicast frames are actually being transferred along the designed transmission routes, so-called “multicast tree monitoring” is performed by for example the carriers at various times such as the start of transmission of the video information or at the time of occurrence of a fault. The present invention refers to a method and a system for such “multicast tree monitoring”.
Note that as known technology related to the present invention, there is the following Patent Document 1. This Patent Document 1 describes to
“set a field management process (FM) on a network, set field client processes (FC) at the hosts (1 to 3), set a subnet monitoring process (SM) in each subnet, have the field management process (FM) decide the connection points between the subnets when the field management process (FM) receives a request for generation of an information bus as a means for communication among a plurality of terminals on the network via the field client processes (FC) from the user, and emit and set instructions for setting multicast tunneling to the subnet monitoring processes (SM) in response to this so that the terminals designate the multicast addresses and transmit “data and dynamically generate the information bus which supports communication between groups”
so as to thereby dynamically construct a logical multicast network and promote efficient utilization of computer resources and network resources.
Further, as prior art known to persons skilled in the art, there is the technique of multicast monitoring explained with reference to FIG. 28 and FIG. 29 explained later. However, the technique of this prior art has problems as will be described later.
[Patent Document 1] Japanese Patent Publication (A) No 2001-156855.